Electric lamp



T.. A. EDISON. Electric Lamp.

(Model) No- 9,150. Patented March22, 1881.

N. PETERS, FHOTO-UINOGHAPHER, WASHINGTON n c UNITED STATES PATENT()FFICE.

THOMAS AVEDISON, OF MENLO PARK, NFAV JERSEY.

ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 239,150, dated March22, 1881,

Application filed August 6, 1880. (ModeL) To all whom it may concern Beit known that I, THOMAS A. EDISON, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented a new and usefulImprovement in Electric Lamps; and I do hereby declare that thefollowing is a full and exact description of the same, reference beinghad to the accompanying drawings, and to the letters of reference markedthereon.

In a system of electric lighting such as proposed by me, in whichseparate electric lamps devoid of regulating devices are used at theplaces of consumption, the entire regulation for all the lamps beingperformed at the central station, as with water or gas supply, it isessential that a constant electro-motive force or pressure hemaintained; and as in such a system the lamps are arranged upon themultipleare or derived-circuit system, it is essential that there shouldbe a certain standard resistance in each derived circuit. This has beenattained by placing one lamp of such standard resistance in each derivedcircuit.

It is desirable that all lamps used should be of equal lighting value,each giving a certain standard amount of light. This has been attainedby giving each a certain definite or standard amount ofradiating-surface. Ordinarily this radiating-surface has been thatwhich, with the standard pressure or electromotive force and thestandard resistance, should give a light equal to sixteen candles.Sometimes, however, it is desirable in some part of the system to uselamps which each give a much less amount of light--for instance, inchandeliers, where it is desired to divide the total amount of lightproduced among a larger number of lamps than ordinary-that is, that thelight of one (say standard sixteen-candle) lamp be divided between two,three, or four lamps, each of eight, five and one-third, or four candlepower, respectively. To attain this is the object of this invention,which is carried into eflect in the following way, taking for examplethe substitution of two lamps for one in a derived circuit.

In a derived circuit are placed two lamps,

each being carefully provided with an incandescing'conductor of one-halfthe resistance and one-half the radiating-surface of the reandradiating-surface.

sistance and radiating-surface of the incandescing conductor of thestandard lamp of the system. A single circuit-breaker is provided for.both lamps, in order that both shall be turned off or on simultaneously.When desirable, the two lamps may be arranged in one holder, which mayform a bracket, or may form a section of a group of lamps or of achandelier.

In the drawings, Figure 1 is a diagram showing onestandard lamp and twohalflamps in derived circuits from the same main conductor. Fig. 2 is aview of two half-lamps arranged in one holder, and Fig. 3 is a diagramshowing the connections in such holder. 0 0 are the main conductorsleading to and from any suitable source of electric energy at thecentral station. In the multiple are l thereto is a lamp, A, of standardresistance In the multiple are 2 are the two lamps B B, each of whichhas just one-half the radiating-surface and onehalf the resistance of A.One circuit-breaker,

b, is provided, controlling the circuit through I both lamps. As aconsequence, With a uniform standard electro-motive force or pressure,each of these lamps will give one-half the light which A would give.

If it is desired to increase the number, there should be the sameproportion between the number used and the standard resistance andradiating-surface.

For two, three, or more lamps, a suitable holder, F, of insulatingmaterial, is made, sockets S being made therein for each lamp. In eachsocket metallic conducting-plates are placed on opposite sides, as c c dd, for forming contact with metal slips or pieces on the necks of thelamps. The socket may be provided with a plain or screw-threadedaperture,

E, by which it may be attached to the wall as a bracket, or to aframing, so that it may constitute a portion of a group of lamps or of achandelier. Upon the socket is a circuitbreaker consisting of a metallicscrew, D, se- 5 cured in a seat, It, and which may be turned to impingeupon or be cleared from contact with a metal block, 0.

t. The conductor 0 passes through c c to e, and the conductor 0 throughd d to the metal face of the standard lamp of the system, the

fraction being the number used, substantially as set forth.

2. The combination, with one socket or holder I 5 and one derivedcircuit, of one circuit-controller and two or more lamps, each of afractional resistance and radiating-surface of a standard lamp,substantially as set forth.

This specification signed and witnessed this 2c 27th day of July, 1880.

THOS. A. EDISON.

Witnesses:

S. D. Mor'r, WM. CARMAN.

